The present invention relates generally to cooking appliances and in particular to gas burners for cooking appliances.
Generally gas of cooking appliances must meet various industry regulations (e.g. fabric ignition, carbon monoxide, carbon deposit, rapid door closure, etc.) to obtain agency certifications. Meeting these industry regulations can have an impact on the efficiency of the burners. Using conventional design practices, increasing the maximum burner rating while staying within industry regulation tends to adversely impact or compromise burner efficiency. For example, a typical 18,000 Btu/hr burner may meet industry regulations, but have an efficiency of about 30% when compared to lower rated burners which may have efficiencies of about 40%. In addition to the drops in efficiency, the flexibility to use the burners with smaller pots is adversely affected and usually requires the user of the cooking appliance to decrease the gas flow to the burner to avoid flames from excessive travelling up the side of the pot.
A gas flame that has about 100% primary air is stable, produces substantially no carbon monoxide and does not reach outward (e.g. towards edges of a utensil) to obtain additional air when utensils or cookware are placed over the burner. As the primary air percentage decreases, secondary air flow paths must be established to complete the combustion or large carbon monoxide spikes can occur. Generally, conventional gas burners have a primary air percentage as low as about 20% to about 30%. Lower primary air percentages adversely affect the ability to pass tests corresponding to the above-noted industry regulations. Typically, the burner size is increased to compensate for the lower primary air percentages.
It would be advantageous to be able to provide smaller burners that allow for greater efficiency and primary air entrainment percentages while meeting industry regulations.